An existing infrastructure of transmission lines for transmitting low frequency analog or digital signals can, under the right circumstances, comprise a means for transmitting simultaneous high frequency digital signals so long as there are also means for preserving the integrity of the high frequency signal and preventing degradation due to noise or other interference.
For instance, power-lines provide an efficient infrastructure for communications systems. A great advantage to the use of power-lines for communication transmittal is that they provide inherent connection between points, and eliminate the need for separate cabling systems. This advantage has been widely put to use in the context of Ethernet networking. Another possible use of power-line communications systems involves the transmittal of encoded High Definition Multimedia Interface or other audio/video signals along power-lines. In such a system, HDMI or A/V components in one room can be connected to various televisions or monitors throughout a home or office by means of the in-wall power-line system. However, in order to transmit an effective signal along power-lines, it is necessary to provide means for noise filtering and surge protection to both preserve signal integrity and protect components from damage attributable to voltage variations.
Ordinary noise filters are not adequate for this task because they are not designed to differentiate between encoded HDMI or other A/V signals (which need to be preserved and transmitted along the power-line) and high-frequency noise (which needs to be filtered out). In addition, any power-line communication device should have internal surge protection in order to eliminate the risk of damage to downstream electronics associated with over-voltage events. Consequently, in order to take full advantage of a power-line communication system transmitting encoded HDMI or other A/V signals, there is a need for an integrated device that provides effective noise-filtering, preserves the integrity of transmitted signals and also protects downstream components against voltage anomalies.